The Dolphins suffered a major scare Monday when left tackle Jake Long left practice with a right knee injury. But the Dolphins dodged a bullet when an MRI showed only a “tweak,” a source close to the situation told the Post on Monday evening. Long likely suffered a sprained medial collateral ligament, but is expected to be fine for the team’s Week 1 game at Houston.

Long still may not make the trip to Dallas on Wednesday for the final preseason game against the Cowboys, but now the Dolphins don’t have to worry about replacing their All-Pro left tackle for the regular season. Long previously suffered an injury to his left knee in the 2010 preseason that he played with all season.

Rookie second-round pick Jonathan Martin, who is switching to right tackle after starting 37 games at left tackle at Stanford, stayed after practice to work on his left tackle technique, and expects to play more there in Tuesday’s walk-through. Fourth-year pro Lydon Murtha, the primary backup at tackle, has missed the last week of practice with a foot injury. Right guard Artis Hicks, an 11-year veteran, can play right tackle if Martin has to start at left tackle against the Cowboys, and John Jerry can fill in at right guard.

The only other tackles on the roster are Will Barker, Ray Feinga and undrafted free agent Andrew McDonald.